President Luiz Inacio Lula da Silva of Brazil and Michelle Bachelet of Chile said in Sao Paulo they would put the issue before an August 10 meeting of a nascent South American Defence Council in Ecuador.
Spain's foreign minister, Miguel Angel Moratinos, and his Brazilian counterpart, Celso Amorim, simultaneously said in Brasilia that they would demand explanations from Washington over the bases.
The Colombian government's announcement July 15 that three of its military air bases were to be used by the United States as part of joint anti-drug operations has ignited concerns and anger among Colombia's neighbours.
Venezuela and its ally Ecuador have warned the move could aggravate already deep tensions with Colombia.
The two almost went to war last year against Colombia over a raid its army made into Ecuador to destroy a FARC rebel camp.
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